Why do some diesel drivers let them idle?
 

Finished some work I didn't want to do yesterday, so went to gorge on some greasy fast food afterwards. There was a Dodge diesel parked outside the fast food place, the guy walked in, ordered, waited for the order, then sat and ate it, all while the pickup idled there (quieter than I thought though). What is up with all the idling? I have seen folks do this before, mainly when refueling, but it seems to be some folks way of doing business with their diesel pickups. Is there method to their madness?

It an old myth. In the old days everyone use to say it was better to let a diesel idle than to constantly start it. It just not true today. Today's diesels have a lot of emissons that make it bad to idle for extended periods. I will let mine idle if it is going to be just a min (like fueling up, or running in a store to grab a drink), but that's about it. I just read a story on yahoo this morning about this. In the artical it said you burn 1/4 to 1/2 a gallon an hour idleing. Some people think you burn more gas starting the truck then you do idleing. I don't see that.

If I go in for a short and it is really hot or extremely cold I leave it idle. For longer periods I just use my remote start so the truck is cool or toasty when I get in.

I have a question. Why is it ok to leave a diesel running when fueling? Is it because it has no spark plugs? Or at least I could not find any spark plugs.

Pretty much. Diesel fuel ignites under pressure. It takes a whole lot of spark to set it on fire. You ever try to light diesel. Minus a lighter it is almost impossible. Gas on the other hand can be lit with just static electricity. Or at least that's the way I look at it.

I see, I still turn mine off when fueling. I was just checking.

How is the big A treating ya?

I think thats the only time I leave mine idling when refueling...
Plus I love the sound of my 6.0

You should take yahoo with a grain of salt, and anybody else who preaches global warming "green" In that same article their quoted as saying the old myth "replacing your air filter helps your car run efficiently" And yahoo's response was "modern fuel injection engines don't get economy benefits from a clean air filter". They mind as well told people that changing motor oil is a waste of money and not necessary.

Good deal, I thought it seemed like an oldtimer's hangup.

So this goes to the question of the high idle mod. I have not done it, I end up in traffic sitting at lights some, but from what I gather on this mod, it kicks in only when the parking brake is depressed. Therefore, it is a mod more for EXTENDED idling situations...agreed?

lots of reasons to leave a truck idle. Just last week before i had the stc and dummy plugs changed, my truck would not restart when warmed up. had to let it set for hours before it would start. Bad battery same thing, you get burned once being late because you shut a truck off and you wont do that again. But the main reason mine idles so much is my big fat black girlfriend in the passenger seat!!!!!!! My black lab likes to have her a/c on while she listens to her xm radio !!!!!!!!

Yeah I don't buy into the whole global warming thing either. I don't really pay to much attention to what yahoo says. I just thought the quoat about fuel consumption while idleing made a good point. Don't know that I trust the numbers too much, but I do belave that idleing for extended periods is bad and just starting the motor couldn't use more fuel than idleing for say an hour or more.

FiremanPat, funny YOU should mention the issue of difficulty restarting a diesel truck. Back in the day when I was a fire department paramedic, we had a traumatic code on one of our outlying freeways, partner shut the darn medic (diesel) truck off...and it would not start. We had to call in another one, never allowed that to happen again. But for mine, never has been an issue. I shut it down after cool down to save fuel costs mostly.

Another reason some argue about letting it continue to run is longevity on the motor and it's bearings. Some engineers say starting a motor without oil pressure up to normal psi adds wear to all the surfaces.

Also, increased wear to the starter and charging system.

I always turn mine off for refueling because I have read that it messes up the overhead computer's data...but I would guess that it would re-configure itself shortly after driving off.

Same here...only let her idle until shes down to 350*F or less...if its extremely hot and I want to run the AC (puts serious load on alt volts output without higher rpms) or extremely cold when I want to keep the heat running...either way in those cases...high idle mod comes into play. Just used it today. Like texans stated...diesel's are compression ignition (extreme ...intense pressure creates tremendous heat and in turn ignites the fuel). Also since we're not hendered by evaporative emissions issues, we can fill-up without our fuel system pressurized (fuel cap off). Any gasser these days tries that and it will result in a CEL.

Hey Moyock, Pretty soon your going to need a whole page for your Signature..Luv it...:-bigparty